A big part of the Mood of the game is the contrast between different factors, like the island vs. the pirates, the land vs. the sea, calm and reserved vs. crude and rambunctious, etc.
All examples shown below may be outdated!!
The island sound
Low-energy, more serious. Downtempo, bordering on ambient for some tracks. More quiet and reserved to match the grounded, melancholic feel of the island interior. Typically not that complex melodically; there’s a big emphasis on steady, driving beats and slow, pad-like instruments - good for playing for extended periods of time as you make your way through levels. Usually has a soft cassette tape filter somewhere in the mix. Mysterious.
Examples
Undertow
Slowjam 3
XtremeConga
Dungeon
Cloud Cover
The pirate sound
Loud and crunchy. Much more focused on melody. Often inspired by sea shanties. A lot of songs channel the rowdy / flamboyant attitude a lot of the castaways have. Heavy on accordion and big crushing drum loops. Lots of soundfont usage. Ideally will play in areas with plot significance or where something important is happening
Examples
Seven Seas
Ghostship
The Sea Gazes Back
Boardwalk
Beachwaltz
RevealFight